Adenovirus (Ad) early region 3 (E3) proteins that affect class I MHC- and TNFalpha-dependent host responses will be studied in vivo. Ad infections can be serious and even fatal in otherwise normal hosts especially children as well as cause fatal hepatic necrosis in immunosuppressed patients. It is therefore important to understand Ad pathogenesis and the effect of the E3 genes on this process. For some of the experiments in this proposal, E3 DNA has been introduced as a transgene in mice and expression of E3 mRNAs and proteins have been partially characterized. For other experiments, the E3 genes will be delivered in various human adenoviral constructs (wt and mutant), some of which have been shown to be pathogenic in liver. Individual E3 genes will be inserted also into the mouse Ad (MAV-1 or FL) that unlike most human Ads does not appear to have immunoregulatory genes in its E3 region. These studies will be facilitated by our recent discovery that MAV-1 causes a strain specific hemorrhagic encephalomyelitis that occurs in C57BL/6 mice but not in BALB/c. With these models, it will be possible to study the effects of acute murine disease and persistence of: (1) Ad gp19K, an E3 protein that downregulates transport of some class I MHC proteins from the endoplasmic reticulum to the cell surface, and thus reduces the cytotoxic T lymphocyte response to infection; (2) Ad E3 14.7K or the complex of 10.4K/14.5K proteins that inhibit the cytolytic activity of TNFalpha. The 10.4K and 14.5K proteins also accelerate internalization of the epidermal growth factor receptor whose effect on Ad disease is unknown. These studies involve matings to insert the E3 transgene into mice of different MHC haplotypes, because Ad gp19K binds preferentially to H-2/g and not H-2/k class I MHC molecules. To understand some of the organ and cell specific effects that will emerge from these pathogenesis studies, in situ techniques will be developed to measure the sites of E3 transgene activity induced by MAV-1.